Problem: $ { {5} \times \left[\begin{array}{rr}{1} & {2} \\ {-2} & {3} \\ {0} & {-1}\end{array}\right] = {?} } $
Explanation: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rr}{5}\times{1} & {5}\times{2} \\ {5}\times{-2} & {5}\times{3} \\ {5}\times{0} & {5}\times{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{5} & {10} \\ {-10} & {15} \\ {0} & {-5}\end{array}\right]}$